Touch sensing apparatus and method for assembly

ABSTRACT

A touch sensing apparatus is disclosed comprising a panel that defines a touch surface, a plurality of light emitters and detectors arranged along a perimeter of the panel. The light emitters are arranged to emit a respective beam of emitted light that travels above the touch surface, wherein the light detectors are arranged to receive detection light from the emitted light. The plurality of light emitters and detectors are arranged above the touch surface and are connected to a substrate extending in a direction parallel with a normal axis of a plane in which the panel extends. A method of assembling a touch sensing apparatus is also disclosed.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND Field of the Invention

The present invention relates to touch-sensing apparatus that operate bypropagating light by diffusive light scattering above a panel, and inparticular to optical and mechanical solutions for defining the lightpaths and control of curvature of the panel. The present inventionrelates furthermore to a method of assembling a touch sensing apparatus.

Background of the Invention

In one category of touch-sensitive panels known as ‘above surfaceoptical touch systems’, a set of optical emitters are arranged aroundthe periphery of a touch surface to emit light that is reflected totravel above the touch surface. A set of light detectors are alsoarranged around the periphery of the touch surface to receive light fromthe set of emitters from above the touch surface. An object that touchesthe touch surface will attenuate the light on one or more propagationpaths of the light and cause a change in the light received by one ormore of the detectors. The location (coordinates), shape or area of theobject may be determined by analysing the received light at thedetectors.

In a variant of such ‘above surface optical touch system’, illustratedin FIG. 1a in cross-section, the emitters 301 are arranged on asubstrate 304, and light from the emitters travel above the touchsurface 302 of the panel 305 via reflection or scattering on an edgereflector or diffusor 303. As shown in top-down view FIG. 1b , the lightwill then continue until deflected by a corresponding edge reflector atan opposing edge of the light transmissive panel, where the light willbe scattered back down through the transmissive panel and onto thedetectors 306.

Detectors 306 are distributed around the periphery of touch surface 302,to receive part of the propagating light. The light from each ofemitters 301 will thereby propagate inside the transmissive panel 305 toa number of different detectors 306 on a plurality of light paths D. Inthe illustrated example, the apparatus 300 also includes a controller320 which is connected to selectively control the activation of theemitters 301 and, possibly, the readout of data from the detectors 306.Depending on implementation, the emitters 301 and/or detectors 306 maybe activated in sequence or concurrently. The signal processor 330 andthe controller 320 may be configured as separate units, or they may beincorporated in a single unit. One or both of the signal processor 330and the controller 320 may be at least partially implemented by softwareexecuted by a processing unit 340.

A problem with such previous systems is the cumbersome alignment betweenthe components thereof, which makes assembly more difficult and costly.Sub-optimal alignment results in signal loss, which moreover is aninherent problem in previous solutions due to the multiple componentsinvolved in the light scattering process. Another issue affecting thesignal and scattering of the light in the touch sensing apparatus isuncontrolled glass warpage, i.e. distortions of the curvature of thelight transmissive panel which will affect the light path and thedetection process. While it is critical to accurately control suchdistortions, previous solutions incorporate complex solutions that maynot allow to fully optimize glass warpage control in a mass productionline without limiting the throughput of the production.

Some prior art systems rely on coupling and propagation of collimatedlight across the light transmissive panel. Such systems are howevercumbersome to reliably implement due to the small tolerances withrespect to the alignment of the components thereof. E.g. the lightemitters- and detectors need to be precisely aligned in relation tovarious lenses and reflect the light via concave and/or convexreflection and/or refraction to get the desired collimation. Suchprecise alignment may be difficult to achieve in mass production. Theuse of collimated light, or light reflected by means of specularreflection, also adds to this complexity, which in turn results in amore expensive and less compact system. Furthermore, to reduce systemcost, it may be desirable to minimize the number of electro-opticalcomponents.

SUMMARY OF THE INVENTION

An objective is to at least partly overcome one or more of the aboveidentified limitations of the prior art.

One objective is to provide a touch-sensitive apparatus based on“above-surface” light propagation which is robust and easy to assemble.

Another objective is to provide an “above-surface”-based touch-sensitiveapparatus with efficient use of light.

One or more of these objectives, and other objectives that may appearfrom the description below, are at least partly achieved by means oftouch-sensitive apparatuses according to the independent claims,embodiments thereof being defined by the dependent claims.

According to a first aspect, a touch sensing apparatus is providedcomprising a panel that defines a touch surface, a plurality of lightemitters and detectors arranged along a perimeter of the panel. Thelight emitters are arranged to emit a respective beam of emitted lightabove the touch surface, wherein the light detectors are arranged toreceive detection light from the emitted light. The plurality of lightemitters and detectors are connected to a substrate extending in adirection parallel with a normal axis of a plane in which the panelextends.

Preferably the plurality of light emitters and detectors are arrangedabove the touch surface.

Preferably the substrate extends at least partly above the touchsurface, whereby the plurality of light emitters and detectors areconnected to a portion of the substrate extending above the touchsurface.

Preferably the substrate is fixed to a carrier mounted around theperimeter of the panel.

Preferably the carrier is arranged to at least partly enclose edges thepanel.

Preferably the carrier comprises fixing elements configured to attachthe carrier to a display unit.

Preferably the fixing elements are configured to attach the position ofthe substrate in relation to the carrier and/or in relation to thedisplay unit.

Preferably the fixing elements are configured to interlock with amounting element for locking the position of the carrier and/or thesubstrate to the display unit.

Preferably the fixing elements comprise openings, wherein the carrierforms a cavity having walls at least partly enclosing the substrate, andwherein at least one of the walls comprises at least one of saidopenings.

Preferably the fixing elements comprise openings arranged in the carrierand in the substrate, wherein first openings of the carrier are alignedwith second openings of the substrate, the first and second openingsbeing configured to receive a mounting element configured to lock theposition of the carrier and/or the substrate to the display unit.

Preferably the carrier is configured to be attachable to the displayunit at an adjustable position along a direction parallel to the normalaxis, whereby a distance between the panel and the display unit alongthe normal axis is variable upon attaching the carrier to the displayunit at least two different adjustable positions.

Preferably the fixing elements are configured to attach the carrier tothe display unit at the adjustable positions along the directionparallel to the normal axis.

Preferably the openings are separated along a direction parallel to thenormal axis, and/or wherein the carrier is attachable to a plurality ofsecond openings in a display support of the display unit, the pluralityof second openings being separated along the normal axis.

Preferably the carrier is formed from a single monolithic piece ofmaterial.

Preferably the substrate extends in a longitudinal direction along theperimeter of the panel, the substrate comprising secondary fixing unitsconfigured for variably attaching the position of the substrate on thecarrier along the longitudinal direction and/or in the direction of thenormal axis.

Preferably vertical alignment units are arranged between adjacentsubstrates extending in a longitudinal direction along the perimeter ofthe panel, wherein the vertical alignment units are configured tovariably position the adjacent substrates in the direction of the normalaxis so that an angle between the adjacent substrates is adjustable.

Preferably a plurality of substrates extend in a longitudinal directionalong the perimeter of the panel, wherein a first substrate of saidplurality of substrates comprises a connection unit configured todirectly interlock with a subsequent connection unit of a subsequentsubstrate when arranged adjacent said subsequent substrate.

Preferably a sealing window is arranged around the perimeter of thepanel, wherein the sealing window comprises a first surface facing thelight emitters or the light detectors and an opposite second surfacearranged adjacent the touch surface, whereby the emitted or detectedlight propagates between the first and second surface, and wherein atleast one of the first and second surfaces comprises a light collimatingsurface configured to collimate light propagating above the touchsurface.

Preferably the second surface extends in the direction of the normalaxis between a base surface of the sealing window, facing the panel, andan opposite top surface of the sealing window, wherein the base surfaceis offset from the top surface along the direction of the plane with anoffset distance so that the second surface forms an angle relative thenormal axis, and wherein the second surface comprises a lightcollimating surface.

According to a second aspect, a touch sensing apparatus is providedcomprising a panel extending in a plane having a normal axis, the paneldefining a touch surface, a plurality of light emitters and detectorsarranged along a perimeter of the panel, wherein the light emitters arearranged to emit a respective beam of emitted light above the touchsurface, wherein the light detectors are arranged to receive detectionlight from the emitted light. The touch sensing apparatus comprises asealing window arranged around the perimeter, wherein the sealing windowcomprises a first surface facing the light emitters or the lightdetectors and an opposite second surface arranged adjacent the touchsurface, whereby the emitted or detected light propagates between thefirst and second surface, wherein the second surface extends in thedirection of the normal axis between a base surface of the sealingwindow, facing the panel, and an opposite top surface of the sealingwindow, wherein the base surface is offset from the top surface alongthe direction of the plane with an offset distance so that the secondsurface forms an angle relative the normal axis, and wherein the secondsurface comprises a light collimating surface configured to collimatelight propagating above the touch surface.

Preferably the first surface and/or second surface form a curved edgeconvex to the sealing window.

According to a third aspect, a method of assembling a touch sensingapparatus is provided comprising; attaching a substrate having aplurality of light emitters and detectors to a carrier; attaching thecarrier around a perimeter of a panel and arranging the substrate toextend in a direction parallel with a normal axis of a plane in whichthe panel extends.

Preferably the plurality of light emitters and detectors are arrangedabove the touch surface.

Preferably the carrier if formed from a single monolithic piece ofmaterial, the carrier forming a cavity having walls at least partlyenclosing the substrate, wherein at least one of the walls compriseopenings, the method comprising fixing the carrier to a display unit byfixing mounting elements through said openings.

Preferably the method comprises adjusting a distance between the paneland a display unit along the normal axis by attaching the carrier to thedisplay unit at least two different adjustable positions along adirection parallel to the normal axis.

Preferably the method comprises adjusting a radius of curvature of thepanel in the direction of the normal axis by attaching the carrier to adisplay unit at least two different adjustable positions along adirection parallel to the normal axis.

According to a fourth aspect there is provided a touch sensingapparatus, comprising: a panel that defines a touch surface, a pluralityof light emitters and detectors arranged along a perimeter of the paneland the light emitters are arranged to emit a respective beam of emittedlight above the touch surface, and the light emitters are arranged toreceive detection light from the emitted light, a substrate on which theplurality of light emitters and detectors are mountable; and a sealingwindow sealable against at least one surface of the touch sensingapparatus for sealing a cavity around the plurality of light emittersand detectors wherein the sealing window comprises at least onereference surface for aligning the substrate with respect to the sealingwindow.

Preferably the sealing window is sealable between the touch surface anda surface of the substrate.

Preferably the surface of substrate is a surface of a carrier forprotecting components of the touch sensing apparatus.

Preferably the carrier comprises an upper portion which overlaps aportion of the perimeter of the panel and the sealing window is sealablebetween the touch surface and the underside of the overlapping upperportion.

Preferably the at least one reference surface is arranged to engage witha reciprocal reference surface on the substrate.

Preferably the at least one reference surface comprises a first portionfor aligning in a first direction and a second portion for aligning in asecond direction.

Preferably the at least one reference surface aligns the sealing windowwith respect to the substrate in a plane parallel with the touchsurface.

Preferably the at least one reference surface aligns the sealing windowwith respect to the substrate at a height above the touch surface.

Preferably the sealing window comprises at least one resilientlydeformable seal engagable with the substrate.

Preferably the resiliently deformable seal comprises the at least onereference surface.

Preferably the seal is extrudable along one or more surfaces of thesealing window.

Preferably the at least one reference surface substantially extends theentire length of the sealing window.

Preferably the sealing window and/or the substrate comprise a projectionhaving a cross-sectional shape for positive engagement with a reciprocalhole in the substrate and/or sealing window and the at least onereference surface is part of the projection.

Preferably the sealing window and/or the substrate comprise aresiliently deformable projection wherein the projection comprises theat least one reference surface comprises and the projection isdeformable on engagement with the substrate and/or sealing window andforms a snap-fit engagement therebetween.

Preferably the sealing window comprises a plurality of referencesurfaces.

Preferably the at least one reference surface comprises at least onediscrete upstanding projection for engagement with reciprocal hole inthe substrate.

Preferably the at least one upstanding projection is one or more of,pegs, hooks, latches, clamps or fasteners.

According to a fifth aspect there is provided a method of manufacture ofthe touch sensing apparatus comprising: mounting a plurality of lightemitters and detectors to a substrate, attaching the substrate around aperimeter of a panel; and mounting a sealing window against at least onesurface of the touch sensing apparatus for sealing a cavity around theplurality of light emitters and detectors wherein the sealing windowcomprises at least one reference surface for aligning the substrate withrespect to the sealing window.

Further examples of the invention are defined in the dependent claims,wherein features for the second aspect of the disclosure are as for thefirst aspect mutatis mutandis.

Some examples of the disclosure provide for a touch sensing apparatusthat is easier to manufacture and assemble.

Some examples of the disclosure provide for a touch sensing apparatuswith fewer steps of assembly.

Some examples of the disclosure provide for a touch sensing apparatusthat is less costly to manufacture.

Some examples of the disclosure provide for a facilitated alignment ofemitters and detectors of touch sensing apparatus.

Some examples of the disclosure provide for facilitated control of thecurvature of the touch surface of a touch sensing apparatus.

Some examples of the disclosure provide for a more robust touch sensingapparatus.

Some examples of the disclosure provide for a touch sensing apparatusthat is more reliable to use.

Some examples of the disclosure provide for a touch sensing apparatusthat has a better signal-to-noise ratio of the detected light.

Some examples of the disclosure provide for a more compact touch sensingapparatus.

Still other objectives, features, aspects and advantages of the presentdisclosure will appear from the following detailed description, from theattached claims as well as from the drawings.

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps or components but does not preclude thepresence or addition of one or more other features, integers, steps,components or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which examples ofthe invention are capable of will be apparent and elucidated from thefollowing description of examples of the present invention, referencebeing made to the accompanying drawings, in which;

FIG. 1a is a section view of a touch sensing apparatus according to theprior art;

FIG. 1b is a top-down view of a touch sensing apparatus according to theprior art;

FIG. 2 is a schematic illustration, in a cross-sectional side view, of atouch sensing apparatus according to one example;

FIG. 3 is a schematic illustration, in a perspective side view, of atouch sensing apparatus according to one example;

FIG. 4a is a schematic illustration, in a side view of FIG. 2, of atouch sensing apparatus according to one example;

FIG. 4b is a schematic illustration of a magnified section of FIG. 4a ,according to one example;

FIG. 4c is a schematic illustration of a magnified section of FIG. 4a ,according to one example;

FIG. 5a is a schematic illustration, in a cross-sectional side view, ofa touch sensing apparatus according to one example;

FIG. 5b is a schematic illustration of a magnified section of FIG. 5a ,according to one example;

FIG. 6 is a flow chart of a method of assembling a touch sensingapparatus according to one example;

FIG. 7 is a schematic exploded perspective view of different layers ofthe touch-sensing apparatus according to one example;

FIG. 8 is a perspective schematic view of through a cross section of thetouch sensing apparatus according to one example;

FIG. 9 is a cross sectional view of the touch sensing apparatusaccording to one example;

FIG. 10 is a cross sectional view of the touch sensing apparatusaccording to one example;

FIG. 11 is a cross sectional view of the touch sensing apparatusaccording to one example;

FIG. 12 is a perspective schematic view of through a cross section ofthe touch sensing apparatus according to one example;

FIG. 13 is a schematic perspective view of the touch sensing apparatusaccording to one example;

FIG. 14 is a cross sectional view of the touch sensing apparatusaccording to one example;

FIGS. 15a, 15b, 15c, and 15d show magnified cross-sectional views of thetouch sensing apparatus according to different examples; and

FIG. 16 is a schematic perspective view of the touch sensing apparatusaccording to one example.

DETAILED DESCRIPTION

In the following, embodiments of the present invention will be presentedfor a specific example of a touch-sensitive apparatus 100. Throughoutthe description, the same reference numerals are used to identifycorresponding elements.

FIG. 1a schematically illustrates a variant of an ‘above surface opticaltouch system’, as discussed in the Background Art section above, wherethe light from the emitters 301 travel above the touch surface 302 ofthe panel 305 via reflection on an edge reflector 303. FIG. 1billustrates a top plan view of FIG. 1a in an example of atouch-sensitive apparatus 100.

FIG. 2 schematically illustrate a touch sensing apparatus 100 comprisinga light transmissive panel 101 that defines a touch surface 102. In someembodiments the light transmissive panel 101 is located above a display113 and permits light generated by the display 113 to propagatetherethrough. However in other embodiments the light transmissive panel101 can comprise light blocking material and does not permit thetransmission of light therethrough. For example, the touch sensingapparatus 100, can be a trackpad or another touch interface which isremote from the display unit 113. Hereinafter the term “lighttransmissive panel” 101 will be used to describe either a lighttransmissive panel 101 or a solid, opaque panel 101.

A plurality of light emitters 103 and detectors 103′ are arranged alonga perimeter 104 of the light transmissive panel 101. The light emitters103 are arranged to emit a respective beam of emitted light 105 abovethe touch surface 102. I.e. while the touch surface 102 extends along aplane 108, having a normal axis 107 directed towards a user performingtouch operations on the touch surface 102, the emitted light 105 travelsparallel with plane 108 and at a certain distance from the touch surface102 in the direction of the normal axis 107, as schematicallyillustrated with respect to light beam 105, 105′, in e.g. FIG. 2. Light105, 105′, can thus travel across the touch surface 102, betweenopposite sides thereof, without being reflected inside the lighttransmissive panel 101 itself.

In other embodiments, the plurality of light emitters 103 and detectors103′ are optionally arranged along a perimeter 104 of the lighttransmissive panel 101 at a different height. In some embodiments, thelight emitters 103 and/or detectors 103′ are arranged to emit arespective beam of emitted light 105 below the touch surface 102 and thelight beams are guided around the light transmissive panel 101. Thelight beams can be guided around the light transmissive panel 101 withadditional reflective components (not shown). For the purposes ofbrevity, the embodiments discussed hereinafter refer to the plurality oflight emitters 103 and detectors 103′ being arranged above the touchsurface 102, but the embodiments also include the arrangement where theplurality of light emitters 103 and detectors 103′ are mounted below thetouch surface 102.

The light detectors 103′ are arranged to receive detection light 105′from the emitted light 105. FIG. 2 illustrates a section of the touchsensing apparatus 100 adjacent the perimeter 104 of the lighttransmissive panel 101. In this section, the emitters and detectors 103,103′, are shown in the same view, as well as the emitted and detectedlight 105, 105′, for clarity of presentation. The plurality of lightemitters and detectors 103, 103′, are arranged above the touch surface102 and are connected to a substrate 106 extending in a direction 107′parallel with a normal axis 107 of a plane 108 in which the lighttransmissive panel extends. By having the substrate 106 extending inparallel with the normal axis 107, the plurality of emitters anddetectors 103, 103′ are conveniently arranged, above the touch surface102 to achieve a compact footprint in the direction of the plane 108 ofthe touch sensing apparatus 100 around the perimeter 104, whileachieving a direct light path for the emitted or detected light 105,105′, above and across and touch surface 102. Thus, the emitted light105 does not have to be reflected in order to diffusively spread aboveand across the touch surface 102, and a detector 103′ may directlyreceive detection light 105′ by being correspondingly positioned abovethe touch surface 102 at an opposite position anywhere around theperimeter 104. The amount of available light that can be utilized forthe detection and characterization of an object touching the touchsurface 102 can thus be maximized, and the signal to noise ratio can beimproved. The touch sensing apparatus 100 may comprise a sealing window126 as illustrated in FIG. 2, shielding the emitters and detectors 103,103′, from the outside. The emitted and detected light 105, 105′, maythus only have to propagate through the sealing window 126 along thelight path between the emitters and detectors 103, 103′. The sealingwindow 126 provides sealing around the perimeter 104 of the lighttransmissive panel 101 and protects the emitters and detectors 103, 103′and the display.

Having the substrate extending in the direction 107′ being parallel withthe normal axis 107 and the emitters and detectors 103, 103′, arrangedabove the touch surface 102 provides for a less complex alignment tomaximize the detection performance of the touch sensing apparatus 100.The position of the substrate 106 in the direction of the normal axis107 can be accurately varied to achieve optical alignment with respectto the emitters and detectors 103, 103′. The ability to achieve anaccurate positioning of the substrate 106, and consequently the emittersand detectors 103, 103′, attached thereto, is also due to the increasedaccuracy by which the dimensions of the substrate 106 can be definedalong the direction of the substrate 106 aligned with the normal axis107 in FIG. 2. I.e. the substrate 106 is elongated and extends in alongitudinal direction 123 (FIG. 4a ) around the perimeter 104 of thelight transmissive panel 101, and it has a short-side extending inparallel with the normal axis 107. The short-side of the substrate 106,illustrated in the cross-sectional view of FIG. 2, may be manufacturedto smaller tolerances, and by aligning this side with the normal axis107, the tolerances for the alignment of the emitters and detectors 103,103′, along the normal axis 107 can be improved. The alignment can thusbe both improved, and facilitated as discussed above. The latteradvantage also provides for facilitated and less costly mass productionof the touch sensing apparatus 100 and the various touch base displaysystems in which it may be implemented.

The substrate 106 may extend at least partly above the touch surface102, whereby the plurality of light emitters and detectors 103, 103′,are connected to a portion 109 of the substrate extending above thetouch surface 102. This further provides for achieving a more robustalignment of the emitters and detectors 103, 103′, relative to the lighttransmissive panel 101, by being directly joined to the substrate 106,and thereby simultaneously arranged above the touch surface 102. It maybe conceivable however that the emitters and detectors 103, 103′, areconnected to the substrate 106 via connection elements (not shown)extending between the substrate 106 and to a position above the touchsurface 102.

The substrate 106 may be fixed to a carrier 110 mounted around theperimeter 104 of the light transmissive panel 101, as schematicallyillustrated in FIGS. 1a, 1b and 2. By directly joining the substrate 106to the carrier 110 provided around the perimeter 104, the assembly ofthe touch sensing apparatus 100 may be further facilitated, as theamount of components can be kept at a minimum. For example, thesubstrate 106 can be accurately fixed in relation to the carrier 110,due to the small tolerances possible in the direction of the substrate106 aligned in parallel with the normal axis 107 in FIG. 2, as discussedabove. The carrier 110 may for example comprise a cavity 116, asdiscussed further below, being precisely dimensioned to accommodate thewidth of the substrate 106 along the direction 107′, i.e. the short-sideof the substrate 106. Then, accurate positioning of the emitters anddetectors 103, 103′, in relation to the light transmissive panel 101 ispossible as the carrier 110 is mounted around the perimeter 104 thereof.The carrier 110 may extend substantially in the direction 107′ parallelwith the normal axis 107, as with the substrate 107, to achieve acompact mounting around the perimeter 104. In some embodiments thecarrier 110 may also be the substrate 106 or the emitters and detectors103, 103′ are mounted directly to the carrier 110.

Having the substrate 106 fixed to the carrier 110 allows also for havingthe carrier 110 wired as an electrical ground reference layer of thesubstrate 106.

The carrier 110 may be arranged to at least partly enclose edges 111 ofthe light transmissive panel 101, as shown in the example of FIG. 2.This provides for further increasing the robustness of the touch sensingapparatus 100, and improving the accuracy of the alignment of theemitters and detectors 103, 103′, in relation to the light transmissivepanel 101 since the carrier 110, having the emitters and detectors 103,103′, fixed thereto, may also be directly supporting the lighttransmissive panel 101 around the perimeter 104. The carrier 110 maycomprise a slot in which the light transmissive panel 101 is fittedaround the perimeter 104.

The carrier 110 may comprise fixing elements 112 configured to attachthe carrier 110 to a display unit 113, 121. The display unit maycomprise a display support 121 and a display panel 113, whichcollectively is referred to as a display unit in the present disclosure.Having the carrier 110 attachable to the display unit 113, 121, byfixing elements 112, advantageously provides for further facilitatingthe assembly of the touch sensing apparatus 100 to a display unit, sincethe carrier 110 can be directly joined to the latter. Alignment is thusfacilitated, due to the minimum amount of components needing suchalignment to each other. The robustness of the touch sensing apparatus100 is further improved, while mass production is made less complex duethe minimized number of assembly steps. The fixing elements 112 maycomprise any elements configured to provide for fixing of the positionof the carrier 110 to the display unit 113, 121. In the example shown inFIG. 2, the carrier 110 has openings 115, 115′, 115″, discussed furtherbelow, which may be aligned with corresponding openings 127 of a supportof the display unit 121, through which mounting elements 114 may bepositioned for the fixing. It is conceivable however that the carrier110 has other types of recesses or protrusions which may interlock witha corresponding mating surface of the display unit 113, 121.

The fixing elements 112 may be configured to fix the position of thesubstrate 106 in relation to the carrier 110. Thus, besides from fixingthe position of the carrier 110 relative to the display unit 113, 121,the fixing elements 112 may also fix or at least support the position ofthe substrate 106 in relation to the carrier 110. It is conceivable thatthe substrate 106 may first be arranged in relation to the carrier 110,and the fixing elements 112 may be arranged to support and strengthenthe fixing therebetween, while simultaneously fixing the carrier 110 tothe display unit 113, 121. This may further provide for increasing thestability and ultimately accuracy of the touch sensing apparatus 100.From a similar aspect, the fixing elements 112 may be configured to fixthe position of the substrate 106 in relation to the display unit 113,121. This may be seen as a consequence from the above, i.e. the fixingelements 112 contributing to the fixing of the substrate 106 to thecarrier 110, which in turn is fixed to the display unit 113, 121. It ishowever conceivable that the fixing elements 112 may fix the substrate106 directly to the display unit 113, 121, in which case the carrier 110may act as a further support for the substrate 106.

In one example, as discussed further below, the substrate 106 maycomprise second openings 118 which provides for such fixing or support.As mentioned, this may further provide for increasing the stability andultimately accuracy of the touch sensing apparatus 100.

The fixing elements 112 may be configured to interlock with a mountingelement 114 for locking the position of the carrier 110 and/or thesubstrate 106 to the display unit 113, 121. FIGS. 2-3 show examples ofhaving an elongated mounting element 114 joining the carrier 110 and/orthe substrate 106 to the display unit 113, 121. The mounting element 112may however comprise any fastening element configured to exert a forcebetween the carrier 110 and/or the substrate 106 to the display unit113, 121, such as pins, bolts, screws, clips, clamps, locks, bars, rods,anchors, latches, clasps.

The fixing elements 112 may comprise openings 115, 115′, 115″, asillustrated in FIGS. 2-3. The carrier 110 may form a cavity 116 havingwalls 117 at least partly enclosing the substrate 106, illustrated inthe example of FIG. 2. This may provide for increased stability of thefixing of the position of the substrate 106 in relation to the carrier110. At least one of the walls 117 may comprise at least one of theopenings 115, 115′, 115″, as further illustrated in FIG. 2. Being ableto directly fix the walls 117 of the carrier 110 enclosing the substrate106 to the display unit 121, 113, provides for further simplifyingmanufacturing, and at the same time further increase the accuracy of thealignment of e.g. the emitters and detectors 103, 103′, in relation tothe light transmissive panel 101, since the minimized number ofintermediate mounting components improves tolerance control. I.e.build-up of mounting errors in each assembly step is reduced andcontrolled. It is conceivable that the walls 117 may be fixed to thedisplay unit 113, 121, by other fixing elements 112, such as recesses orprotrusions interlocking with correspondingly mating surfaces of thedisplay unit 113, 121, and/or fastening elements as exemplified above.

The fixing elements 112 may comprise openings 115, 115′, 115″, 118,arranged in the carrier 110 and in the substrate 106. First openings115, 115′, 115″ of the carrier 110 may be aligned with second openings118 of the substrate 106, as illustrated in the example of FIG. 2. Thefirst and second openings 115, 115′, 115″, 118 may be configured toreceive a mounting element 114 configured to lock the position of thecarrier 110 and/or the substrate 106 to the display unit 113, 121. Thisprovides for further facilitated and improved alignment and assembly,and increased robustness. In the example of FIG. 2, the carrier 110encloses the substrate 106 such that two opposite openings 115, 115″, ofthe carrier are arranged on either side of the substrate 106, but it isconceivable that the carrier 110 may be arranged on one side only of thesubstrate 106.

The carrier 110 may be configured to be attachable to the display unit121, 113, at an adjustable position 119, 119′, along a direction 117″parallel to the normal axis. A distance 120 between the lighttransmissive panel 101 and the display unit 113 along the normal axis107 may thus be variable upon attaching the carrier to the display unit113, 121 at least two different adjustable positions 119, 119′. Forexample, turning to FIG. 3, the carrier 110 is attached at a firstposition 119 to the support of the display unit 121, via fixing unit112. The first position 119 provides for the given distance 120 betweenthe panel of the display unit 113. The distance 120 may then bedecreased by instead attaching the carrier 110 at a second position 119′which is off-set with respect to the first position 119 in the positivedirection of the normal axis 107, or the direction 107″ as illustratedin FIG. 3. If the fixing point to the support of the display unit 121remains constant, e.g. at the opening 127 of a support 121 asillustrated, the carrier 110 will be moved in the opposite direction tothe normal axis 107 and the distance 120 will be decreased. Having thecarrier 110 being attachable to the display unit 121, 113, at anadjustable position 119, 119′, along a direction 117″ parallel to thenormal axis 107, thus provides for simple and efficient adjustment ofthe position of the light transmissive panel 101.

Besides from overall controlling the distance 120, as discussed, suchadjustment provides for efficiently controlling and varying thecurvature of the light transmissive panel 101. I.e. varying the distance120 as discussed at a second intermediate location 128′, betweenopposite ends of the carrier 110, along the longitudinal direction 123,while maintaining the distance 120 at the opposite ends, such as at afirst location 128, will affect the curvature of the carrier 110, andthereby the curvature of the light transmissive panel 101. E.g.decreasing the distance 120 at the second location 128′ can produce amore concave shape, i.e. a decreased radius of curvature, of the carrier110 and the light transmissive panel 101, in the direction of the normalaxis 107. Increasing the distance 120 between the mentioned oppositeends can instead increase the radius of curvature in the direction ofthe normal axis 107. The curvature or warping of the light transmissivepanel 101 can thus be controlled efficiently an in a facilitated manner,which is advantageous for increasing throughput in mass-production ofdisplays incorporating the touch sensing apparatus 100 while keeping thewarp of the light transmissive panel 101 under control. An optimizedcurvature of the light transmissive panel 101 increases the reliabilityand accuracy of the touch sensing apparatus 100.

The fixing elements 112 may be configured to attach the carrier 110 tothe display unit 121 at the adjustable positions 119, 119′, along thedirection 117″ parallel to the normal axis 107. Thus, the fixing units112 be arranged at the different adjustable positions 119, 119′, toadjust the distance 120 and the curvature of the a light transmissivepanel 101 while providing for securely attaching the carrier to thedisplay unit 113, 121. The fixing elements 112 may thus be arranged atleast at the first and second locations 128, 128′, along thelongitudinal direction 123 as discussed above, where each of thelocations in the longitudinal direction 123 may have at least twoadjustable positions 119, 119′, as illustrated in the example of FIG. 3.

The openings 115, 115′, of the carrier 110 may be separated along adirection 117″ parallel to the normal axis 107, as illustrated in FIG.3. Alternatively, or in addition, the carrier 110 may be attachable to aplurality of second openings 122 in a display support 121 of the displayunit, where the plurality of second openings 122 are separated along thenormal axis 107. Thus, the position 119, 119′, may be remained fixedwhile the carrier 110 is attached to the support 121 at the varioussecond openings 122, to adjust the curvature of the light transmissivepanel 101 and/or the distance 120 as discussed above. Although theexamples in FIGS. 2-3, show openings 115, 115′, 115″, 127, it isconceivable that the attachment between the carrier 110 and the displayunit 121, 113, is provided by other fixing elements 112 as exemplifiedabove.

The carrier 110 may be formed from a single monolithic piece ofmaterial. The structural integrity and the stability of the carrier 110can thereby be increased, which further optimizes the parametersdiscussed above with respect to alignment, robustness, ease of assemblyetc. One example of a possible process by which the carrier can beformed as a single piece of material is an extrusion process, but it isconceivable that the carrier 110 may be formed from other hot or coldmetal or polymer working processes such as drawing, rolling, or moldingprocesses.

The substrate 106 may extend in a longitudinal direction 123 along theperimeter 104 of the light transmissive panel 101. FIG. 4a illustrates aview of a plurality of substrates 106, 106′, extending along thelongitudinal direction 123. The light transmissive panel 101 and thecarrier 110 holding the substrates have been excluded in the view forclarity of presentation. The substrates 106, 106′, may comprisesecondary fixing units 124, 124′, configured for variably attaching theposition of each of the substrates 106, 106′, on the carrier 110 alongthe longitudinal direction 123 and/or in the direction of the normalaxis 107. This provides for more accurately adjusting the position ofthe substrates 106, 106′, in relation to the light transmissive panel101. While each of the substrates 106, 106′, may be within tolerances,the accumulated error obtained when several substrates 106, 106′ areconnected along the longitudinal direction 123 may exceed the totaltolerance of the full length of the light transmissive panel 101. Suchaccumulation of errors may be effectively prevented by having secondaryfixing units 124, 124′, as elucidated above. The secondary fixing units124, 124′, may be provided on various locations on the substrates 106,106′, to allow for adjusting the position, such as on opposite endsthereof.

The touch sensing apparatus 100 may comprise vertical alignment units135 arranged between adjacent substrates 106, 106′, extending in alongitudinal direction 123 along the perimeter 104 of the lighttransmissive panel 101. The vertical alignment units 135 are configuredto variably position the adjacent substrates 106, 106′, in the directionof the normal axis 107 so that an angle 136 between the adjacentsubstrates 106, 106′, can be adjusted. FIG. 4b schematically illustratesa vertical alignment unit 135 positioned between adjacent substrates106, 106′, to vary the position thereof in the direction of the normalaxis 107, i.e. along arrows 137, so that the angle 136 may be set to adesired value. The vertical alignment unit 135 thus provides forfacilitating the alignment of the plurality of substrates 106, 106′, toe.g. the curvature of the light transmissive panel 101. For example, ifthe light transmissive panel 101 is concave in the direction of thenormal axis 107, initially parallel substrates 106, 106′, may be angledto closely follow the concave shape of the light transmissive panel 101by increasing the angle 136 between the substrates 106, 106′, asschematically illustrated in FIG. 4b . The position of the emitters anddetectors 103, 103′, on the substrates 106, 106′, may thus remain at anoptimized vertical position relative the light transmissive panel 101for various curvatures thereof. The vertical alignment unit 135 maycomprise various units configured to change the position of the adjacentsubstrates 106, 106′, in the direction of the normal axis 107, such asbolts, screws, pins, or any other elements that can provide an offset atthe ends of the substrates 106, 106′.

The touch sensing apparatus 100 may comprise force distributing units138 positioned between adjacent substrates 106, 106′, configured toprovide a fixing force therebetween, as schematically illustrated inFIG. 4c . The force distributing units 138 may provide for improving andfacilitating the fixing of the substrates 106, 106′, to the carrier,without the need for dedicated fixing elements such as screws, bolts,etc to each end of respective substrates 106, 106′, thereby reducing theamount of such fixing elements, which facilitates the assembly of thetouch sensing apparatus 100.

The touch sensing apparatus may thus comprise a plurality of substrates106, 106′, extending in a longitudinal direction 123 along the perimeter104 of the light transmissive panel 101. A first substrate 106 of theplurality of substrates may comprises a connection unit 125 configuredto directly interlock with a subsequent connection unit 125′ of asubsequent substrate 106′ when arranged adjacent said subsequentsubstrate, as schematically illustrated in FIG. 4a . It is therebypossible to directly connect subsequent substrates 106, 106′, andeliminate the need for intermediate connectors, which further providesfor facilitating the assembly of the touch sensing apparatus 100.

The touch sensing apparatus 100 may comprise a sealing window 126 asschematically illustrated in FIGS. 5a-b . The sealing window 126 may bearranged around the perimeter 104 of the light transmissive panel 101.The sealing window 126 may comprise a first surface 129 facing the lightemitters 103 or the light detectors 103′, and an opposite second surface130 arranged adjacent the touch surface 102. Emitted or detected lightthus propagates between the first and second surface 129, 130. At leastone of the first and second surfaces 129, 130, may comprises a lightcollimating surface 129, 130, configured to collimate light propagatingabove the touch surface 102. I.e. emitted light 105 will be collimatedby the sealing window 126, so that the light propagating above the touchsurface 102 will be collimated. Detectors 103′ will receive thecollimated light which will be focused through a corresponding sealingwindow 126. As the emitters and detectors 103, 103′, are arranged abovethe touch surface 102 and are connected to a substrate 106 extending ina direction parallel with a normal axis 107, it is possible to providefor a very precise and improved alignment thereof in relation to thesealing window 126, which allows for achieving collimated light in ahighly optimized manner, and an associated increase in signal strengthsince more of the emitted light can be collected by the detectors 103′.The emitted light is collimated in a direction parallel with the plane108 in which the light transmissive panel 101 extends. Collimating thelight with sealing window 126 also allows for reducing the aperture ofthe sealing window 126, i.e. the thickness of the sealing window 126 inthe direction of the normal axis 107, while still detecting a sufficientamount of light. This provides for reducing the amount of ambient lightreaching the detectors 103′, thus improving the signal to noise ratio.

Turning to FIG. 5b , the second surface 130 may extend in the directionof the normal axis 107 between a base surface 131 of the sealing window126, facing the light transmissive panel 101, and an opposite topsurface 132 of the sealing window 126. The base surface 131 may beoffset from the top surface 132 along the direction of the plane 108with an offset distance 133 so that the second surface 130 forms anangle 134 relative the normal axis 107. As further illustrated in FIG.5b , the second surface may comprises the light collimating surface 130.Thus, in addition to having a convex shape as illustrated in FIG. 5b ,the second surface 130 is arranged to assume a tilted configuration asprovided by the offset distance 133. Having such angled configurationprovides for reducing the impact of Fresnel reflexes. The Fresnelreflexes otherwise generate additional unwanted light paths that willreduce the apparent attenuation on some detection lines, especially whenthey run parallel to and near a sealing window 126. These Fresnelreflexes may also result in artifacts and false touch information. Byhaving an angled and/or curved second surface 130 of the sealing window126, the light may instead bounce off the second surface 130 with suchan angle so that it leaves the plane 108, and thereby not interfere withthe detection of the remaining light.

A sealing window 126 as described above can provide for the advantageouseffects as described for touch sensing apparatuses having a plurality oflight emitters and detectors arranged in a multitude of configurations,not limited to the configurations described in relation to FIGS. 2 and 3exemplified above. A touch sensing apparatus 100 is thus providedcomprising a light transmissive panel 101 extending in a plane 108having a normal axis 107, wherein the light transmissive panel defines atouch surface 102. The touch sensing apparatus 100 comprises a pluralityof light emitters 103 and detectors 103′ arranged along a perimeter 104of the light transmissive panel, wherein the light emitters are arrangedto emit a respective beam of emitted light 105 above the touch surface,wherein the light detectors are arranged to receive detection light 105′from the emitted light. The touch sensing apparatus 100 comprises asealing window 126 arranged around the perimeter, wherein the sealingwindow comprises a first surface 129 facing the light emitters or thelight detectors and an opposite second surface 130 arranged adjacent thetouch surface, whereby the emitted or detected light propagates betweenthe first and second surface, wherein the second surface extends in thedirection of the normal axis between a base surface 131 of the sealingwindow, facing the light transmissive panel, and an opposite top surface132 of the sealing window, wherein the base surface is offset from thetop surface along the direction of the plane with an offset distance 133so that the second surface forms an angle 134 relative the normal axis,and wherein the second surface comprises a light collimating surface 130configured to collimate light propagating above the touch surface.

The first surface 129, facing the emitters or detectors 103, 103′, mayalso be angled, with an angle 134′, as schematically illustrated in FIG.5a , to provide for the desired light path from or towards the emittersor detectors 103, 103′, respectively. The first surface 129 may alsocomprise a light collimating surface and have a convex shape towards theemitters or detectors 103, 103′, as illustrated in FIG. 5a , in additionto being arranged at an angle 134′. The angles 134, 134′, may be in therange of 2-10 degrees relative to the normal axis 107 to provide for aparticularly advantageous reduction of Fresnel reflexes. An anglegreater than 2 degrees avoids Fresnel reflexes and an angle of less that10 degrees reduces the light field height.

The sealing window 126 may comprise a fixing element 139 configured tointerlock to carrier 110. In the example in FIG. 5a , the fixing elementcomprises a protrusion 139 arranged to interlock with a correspondingrecess in the carrier 110. Mounting and fixing of the sealing window 126may thus be facilitated and improved since the fixing element 139 maysnap into the carrier 110, without needing to have separate fixing unitsor adhesives joining the sealing window 126 to the carrier 110. In somecircumstances, it is preferable not to use an adhesive because theadhesive may not be resilient in high temperatures. Use of an adhesivefor fixing the sealing window 126 can be problematic because the uncuredadhesive allows for relative movement between the components and precisealignment may be difficult. It is conceivable that the fixing element139 may comprise any other shape, such as a recess, for interlockingwith a corresponding mating surface of the carrier 110.

Alternative embodiments of the sealing window 126 will now be describedin reference to FIGS. 7 to 16.

FIG. 7 shows an exploded perspective schematic view of the touch sensingapparatus 100. The dotted line shows the normal axis 107 of the touchsurface 102 at the center of the light transmissive panel 101. For thepurposes of clarity, the exploded perspective view in FIG. 7 shows theseparate components side by side, but the dotted line of the normal axis107 represents the order of how the components stack together. Asmentioned previously the carrier 110 may extend substantially in thedirection parallel with the normal axis 107. In this way the carrier 110comprises a downwardly projecting skirt 700 from the upper surface 702.

The sealing window 126 is mountable on the carrier 110 and this will bediscussed in further detail below. The sealing window 126 comprises asimilar shape to the arrangement of the plurality of light emitters 103and detectors 103′ (not shown in FIG. 7 for the purposes of clarity).The sealing window 126 is mounted such that the plurality of lightemitters 103 and detectors 103′ are between the sealing window 126 andthe skirt 700. As shown in FIG. 7, the sealing window 126 is arectangular loop structure.

In some embodiments, the sealing window 126 may be formed from a singlemonolithic piece of material, thus providing for a robust sealing window126 and a stable attachment to the carrier 110 and the lighttransmissive panel 101. The sealing window 126 may be formed by anextrusion process. In one embodiment, the sealing window is formed fromtwo separate materials. A first material, such as a dyed PMMA or similarNIR transparent material, is used for a transparent section and a secondmaterial, such as a compressible light blocking material, is used forsealing off the E/D compartment. This may be achieved by e.g. using aco-extrusion process.

In other embodiments, the sealing window 126 is formed from a pluralityof longitudinal pieces (not shown) and joined together to form arectangular arrangement. Each longitudinal piece may be a singlemonolithic piece of material. Considering the sealing window 126 in FIG.7, the arrangement as shown in FIG. 7 is formed from four pieces ofextruded sealing window material 126. The four pieces are then joinedtogether to construct the rectangular loop as shown in FIG. 7. The fourpieces of the extruded sealing window 126 can be adhered together withglue, or fastened together with screws, clips, clamps or any othersuitable fastener. The glue can be applied and cured before the sealingwindow 126 is slid into the carrier 110 or the glue can be left to cureonce the sealing window 126 is positioned in the carrier 110.Alternatively the four pieces are not fastened or glued together and areheld in position with a friction fit.

The sealing window 126, once assembled, is sandwiched between the uppersurface 702 of the carrier 110 and the light transmissive panel 101. Insome embodiments, the sealing window 126 is slid into position betweenthe carrier 110 and the light transmissive panel 101. FIG. 8 shows thedirection A in which the sealing window 126 is moved with respect to thecarrier 110 and the light transmissive panel 101. In this embodiment thesealing window 126 is slid in a direction parallel with the plane of thelight transmissive panel 101. In other embodiments, discussed in moredetail below, the sealing window 126 can be inserted into the carrier110 in a different direction such as parallel to the normal axis 107 andperpendicular to the touch surface 102.

In some embodiments the light transmissive panel 101 is not required tobe light transmissive. For example the touch surface 102 can be on amedium through which light does not propagate. In some embodiments thetouch surface 102 can be part of a surface which does not require lightfrom a display unit 113, 121 to be visible there through. That is, thetouch sensing apparatus 100 is remote from the display unit 113, 121 andthe display unit 113, 121 is not stacked together with the othercomponents as shown in FIG. 7. In this way the light transmissive panel101 can be considered to be a panel 101. For the purposes of clarity,the panel 101 has been referred to as a light transmissive panel 101,but all the embodiments are also applicable to a panel comprising anopaque or light blocking material.

Turning to FIG. 8, the construction of the carrier 110, the sealingwindow 126 and the light transmissive panel will now be discussed inmore detail. FIG. 8 shows a partial perspective cross-sectional view ofthe touch sensing apparatus 100. In particular FIG. 8 is magnified toshow the arrangement between the carrier 110, the sealing window 126 andthe light transmissive panel 101.

The sealing window 126 comprises a dual purpose. Firstly, the sealingwindow 126 provides sealing around the perimeter 104 of the lighttransmissive panel 101 and protects the emitters and detectors 103, 103′and the edge of the light transmissive panel 101. This means that thesealing window 126 prevents ingress of dirt, water and othercontaminants into the interior of the touch sensing apparatus 100. Thishelps protect the internal components such as the plurality of emittersand detectors 103, 103′. Secondly, the sealing window 126 allows lightfrom the emitters and detectors 103, 103′ to propagate therethrough. Insome embodiments, as discussed in reference to FIG. 5a , the sealingwindow can optionally comprise optical elements for refracting,deflecting, diverting or focusing the light beams therethrough. Howeverin other embodiments, the sealing window is optically passive and doesnot comprise any optical elements for refracting, deflecting, divertingor focusing the light beams therethrough.

As can be seen from FIG. 8, an upper sealing surface 800 of the sealingwindow 126 engages with an interior underside surface 802 of the carrier110. The upper surface 702 of the carrier 110 is arranged to projectover the light transmissive panel 101. In this way the carrier 110overlaps a portion of the light transmissive panel 101 around theperimeter of the light transmissive panel 101. The portion 810 of theupper surface 702 that overlaps with the light transmissive panel 101 isindicated by a bracket in FIG. 8. The overlapping portion 810 of thecarrier 110 provides protection for the perimeter light transmissivepanel 101 from shock and other physical forces. The overlapping portion810 also provides an overhang on which the sealing window 126 can bemounted. The interior underside surface 802 of the carrier is anopposite face to the upper surface 702. A lower sealing surface 804 ofthe sealing window 126 engages with the touch surface 102.

In order to aid the sealing, the sealing window 126 optionally comprisesone or more deformable seals or integral gaskets 806, 808 mounted on theupper sealing surface 800 and the lower sealing surface 804respectively. The deformable seals 806, 808 are arranged to deform whenthe light transmissive panel 101 is urged towards the carrier 110. Thedeformable seals 806, 808 are extruded along the longitudinal length ofthe sealing window 126. In some embodiments the deformable seals 806,808 are integral with the sealing window 126. As mentioned previously,in some embodiments the deformable seals 806, 808 can be manufactured atthe same time as the sealing window 126 in a co-extrusion process.Alternatively the deformable seals 806, 808 are mounted and adhered tothe sealing window 126 after the sealing window 126 has been extruded.In some embodiments the deformable seals 806, 808 are made from athermoplastic elastomer (TPE). The deformable seals 806, 808 can becolored black to block transmission of light from the sealing window126. The deformable seals 806, 808 can be any suitable color or materialfor absorbing light and minimizing light in-coupling.

In some embodiments the sealing window 126 is configured to be mountedbetween two surfaces for sealing and protecting the emitters anddetectors 103, 103′ from the outside environment. In some embodimentsthe sealing window 126 is arranged to seal against the touch surface 102and the interior underside surface 802 of the carrier 110. In otherembodiments the sealing window 126 can be mounted between any othersurface to provide a sealed cavity 116 around the emitters and detectors103, 103′. In some embodiments the sealing window 126 seals between theinterior underside surface 802 and other surface. The other surface doesnot need to be the touch surface 102. Instead the other surface isanother interior surface of the carrier 110 such as a surface on whichthe substrate 106 is mounted on. In some other embodiments the sealingwindow 126 is mounted and sealed against another components and neitherof the touch surface 102 and the interior underside surface 802. In someembodiments the sealing window 126 is sealable against at least onesurface of the touch sensing apparatus 100 for sealing a cavity 116around the plurality of light emitters and detectors 103, 103′. In someembodiments the carrier 110 may also be the substrate 106 or theemitters and detectors 103, 103′ are mounted directly to the carrier110.

In some embodiments the sealing window 126 comprises at least onereference surface 812 for aligning the sealing window 126 with respectto the carrier 110. The reference surface 812 will be discussed infurther detail with respect to FIG. 9 for the purposes of clarity.

FIG. 9 is a schematic cross-sectional view of the touch sensingapparatus 100. The sealing window 126 is inserted between the lighttransmissive panel 101 and the carrier 110. The upper deformable seal806 comprises a reference surface 812 for aligning the sealing window126 with respect to the carrier 110. The upper deformable seal 806comprises a projection 814 which projects upwardly from the upperdeformable seal 806 and the sealing window 126. In this way, thereference surface 812 is upright with respect to the sealing window 126.The projection 814 also optionally comprises a chamfer 816 in additionto the reference surface 812.

The chamfer 816 means that the deformable upper seal 806 does not snagon the carrier 110 when the sealing window 126 is inserted between thecarrier 110 and the light transmissive panel 101. Accordingly as thesealing window 126 is pushed into place, the chamfer 816 urges againstthe interior underside surface 802 of the carrier 110. Initially, thedeformable upper seal 806 is squashed between the carrier 110 and thelight transmissive panel 101 when the sealing window 126 is being forcedbetween the carrier 110 and the light transmissive panel 101.

The sealing window 126 is pushed towards a notch 820 located in theinterior underside surface 802 of the carrier 110. In some embodiments,the notch 820 is a groove that extends around the periphery of thecarrier 110. The notch 820 comprises a reciprocal reference surface 818for aligning with the reference surface 812 of the projection 814. Inparticular, the notch 820 is a reference point for indicating that thesealing window 126 is inserted underneath the overlapping portion 810sufficiently to form a seal and protect the internal components of thetouch sensing apparatus 100. The notch 820 is positioned a predetermineddistance from the edge 822 of the carrier 110. In some embodiments thepredetermined distance is at least half the width of the sealing window126.

When the sealing window 126 pushed sufficiently between the carrier 110and the light transmissive panel 101, the deformed projection 814 islocated within the notch 820. At this point when the sealing window 126is located in the correct position with respect to the carrier 110, thereference surface 812 abuts against a reciprocal reference surface 818in the notch 820 in the carrier 110.

The compressed projection 814 resiles and expands once located in thenotch 820. In this way, the project 814 snaps into position andpositively engages with the notch 820. When the sealing window 126 islocated and the projection 814 snaps into place, the sealing window 126makes an audible “click”. Additionally or alternatively the snapping ofthe projection 814 into position provides a tactile feedback duringassembly that the sealing window 126 is seated correctly.

The size of the notch 820 is slightly larger than the dimensions of theprojection 814. Accordingly the projection 814 fits snugly within thenotch 820. This means that the frictional forces between the carrier110, the light transmissive panel 101 and the sealing window 126 aresufficient to hold the sealing window 126 in place. Adhesive is notrequired to fix the sealing window 126 in place. However in someembodiments adhesive is optionally used in addition to the snap-fitpositive engagement.

In some embodiments the reference surface 812 abuts against thereciprocal reference surface 818. This means that the sealing window 126opposes the direction A by virtue of the engaged reference surfaces 812,818. Removal of the sealing window 126 may only be achieved with aspecial tool which compresses the projection 814.

Once the sealing window 126 has been seated correctly in the carrier110, the reference surfaces 812, 818 maintain the alignment between thecarrier 110 and the sealing window 126. The deformable seals 806, 808maintain the relative position of the sealing window 126 with respect tothe carrier and prevents lateral movement in a plane parallel to thelight transmissive panel 101. Furthermore, the reference surfaces 812,818 ensure that the sealing window 126 is maintained at a certain heightabove the touch surface 102.

The shape and size of the deformable seal 806, 808 can be varied.Another embodiment with such a variation is shown in FIG. 10. FIG. 10shows a cross sectional side view of the touch sensing apparatus 100.The arrangement is the same as shown in reference to FIGS. 8 and 9,except the cross sectional shape of the deformable seal 806, 808 isdifferent. In this embodiment the projection 1002 comprises a curvedupwardly projecting bulge 1002 on the upper deformable seal 806. Thebulge 1002 comprises a curved reference surface 1004 which engages withone or more reciprocal reference surfaces 818 of the notch 820. Thecurved reference surface 1004 functions in a similar way to the chamfer814 as described in reference to the previous embodiment when insertingthe sealing window 126 between the light transmissive panel 101 and thecarrier 110. The bulge 1002 has dimensions which are substantially thesame width as the width of the notch 820 so that the sealing window 126does not experience lateral movement in a direction parallel with theplane of the light transmissive panel 101. The lower seal 808 optionallycomprises a similar bulge 1006 for engaging and sealing against thetouch surface 102. By making the upper seal 806 and the lower seal 808have the same cross section, manufacture can be simplified because thesame die (not shown) can be used during extrusion of the deformableseals 806, 808.

Advantageously the shape of the projection 1002 means that the sealingwindow 126 can be removed with a similar magnitude of force to the forceneeded for insertion during assembly. Accordingly removal of the sealingwindow 126 may not require a tool. This can make maintenance whichrequires removal of the sealing window 126 easier.

Another embodiment is shown in FIG. 11. FIG. 11 shows a cross sectionalside view of the touch sensing apparatus 100. FIG. 11 is the same asshown in FIG. 10 except that there is an additional projection andnotch. The first notch 1100 and first bulge 1104 are substantially thesame as the notch 820 and the bulge 1002 as discussed in reference toFIG. 10. In addition, there is a second notch 1102 and a second bulge1106. Likewise the lower seal 808 comprises similar first and secondbulges 1108, 1110. Having two projecting bulges 1104, 1106 means thatthere are two points of sealing engagement between the sealing window126 and the light transmissive panel 101 and the carrier 110respectively. This means that there will be less rotation of the sealingwindow 126 about the deformable seal 806, 808. Accordingly, thetolerances needed to accommodate rotational movement of the sealingwindow about the longitudinal axis of the sealing window can be lower.There is also an increased surface area of the deformable seals 806, 808and therefore the deformable seals will cool quicker during manufacture.

In another embodiment, the first and second bulges 1104, 1106 engagewith a single notch 820 as shown in FIG. 10. The dotted line between thefirst and second notches 1100, 1102 represents a single notch, similarto the notch 820 in FIG. 10. In this case the first bulge 1104 engages afirst reciprocal reference surface 1114 and the second bulge 116 engageswith a second reciprocal reference surface 1112. The first and secondreciprocal reference surfaces 1114, 1112 are walls of the notch 820.

Another embodiment will now be discussed in reference to FIG. 12. FIG.12 shows a schematic perspective and cross-sectional view of the touchsensing apparatus 100. The arrangement as shown in FIG. 12 is the sameas shown in FIGS. 8 and 9 except that the deformable seal 806 comprisesa plurality of discrete projections 1200, 1202, 1204. Each of theprojections is deformable and is inserted between the light transmissivepanel 101 and the carrier 110 in the same way as described with respectto the previous embodiments. The carrier 110 comprises a serious ofreciprocal recesses (not shown for clarity) to receive a respectiveprojection 1200, 1202, 1204. In this way less deformable material isrequired to perform the alignment function. The projections may beadhered to the deformable seal material 806 or the projections can beextruded. Each of the projections 1200, 1202, 1204 comprise a referencesurface for aligning the projection and the sealing window 126 with thereciprocal recess in the carrier 110. In some embodiments theprojections 1200, 1202, 1204 can comprise any suitable cross sectionalshape. For example, the projections can comprise an oval curved crosssection, similar to the bulges shown in the embodiments discussed inreference to FIGS. 10 and 11.

FIG. 13 shows yet another embodiment. FIG. 13 shows a schematic explodedperspective view of the touch sensing apparatus 100. For the purposes ofclarity the light transmissive panel 101 is not shown. The sealingwindow 126 is the same as described in reference to the previousembodiments. The upper deformable seal 806 is mounted on the uppersealing surface 800. In contrast to the previous embodiments, thedeformable seal 806 does not comprise upward projections comprising areference surface. Instead the sealing window 126 comprises positioningpegs 1300, 1302 for engagement in the reciprocal positioning holes 1304,1306 located in the carrier 110. In this way the reference surfaces areseparate from the deformable seal 806. Each of the positioning pegs1300, 1302 comprises a reference surface 1308, 1310 for aligning thesealing window 126. In this way as the sealing window is slid underneaththe carrier 110 in the direction A, the pegs 1300, 1302 slot into thepositioning holes 1304, 1306. The holes 1304, 1306 are blind holes andwhen the reference surfaces 1308, 1310 abut the end of the blind holes1304, 1306, the sealing window 126 is in the correct position. The holes1304, 1306 are deep enough such that the sealing window 126 iscompletely under the carrier 110, similar to the arrangement shown inthe previous embodiments.

FIG. 14 shows another embodiment. FIG. 14 shows a cross sectional sideview of the touch sensing apparatus 100. The arrangement as shown inFIG. 14 is the same as shown in FIGS. 8 and 9 except that the projection1400 is formed on the carrier 110 and the notch 1402 is formed in theupper deformable seal 806. In this embodiment the projection 1400 isrigid and downwardly projects from the carrier 110. The notch 1402 isdeformable and snaps into position when the notch 1402 is in positiveengagement with the projection 1400 and reference surfaces are inengagement. The sealing window 126 is inserted between the carrier andthe light transmissive panel 101 in the same way as discussedpreviously.

In alternative embodiments, the carrier 110, the light transmissivepanel 101 and the sealing window 126 are assembled in a different order.The components are the same as described in reference to the previousembodiments. Turning to FIGS. 15a-15d and FIG. 16 the alternative methodof assembly will now be discussed.

FIGS. 15a-15d show a side cross section of the touch sensing apparatus100. The light transmissive panel 101 has been omitted for clarity. Thesealing window 126 is pushed towards the carrier 110 in direction B.That is, a direction which is parallel to normal axis 107. FIG. 15ashows two deformable projections 1500, 1502 which have a snap-fitengagement with reciprocal grooves in the carrier. The deformableprojections 1500, 1502 have a cross sectional shape that snaps into thereciprocal holes when the sealing window is seated correctly in thecarrier 110.

FIG. 15b shows a similar arrangement to FIG. 15a except that there is asingle projection 1504 which does not have a snap-fit engagement.Optionally, positive engagement is provided by the projection 1504having a snug friction fit. When the sealing window 126 cannot move anyfurther with respect to the carrier 110, the projection 1504 will abutthe reciprocal surface of the hole in the carrier 110 and the sealingwindow will be seated correctly.

FIGS. 15c and 15d show stepwise engagement of the same arrangement. Thedeformable seal 806 comprises snap-fit latches 1506, 1508 which bend andsnap into place once the sealing window is fully seated in the carrier110.

Once the sealing window 126 and the carrier 110 are assembled, then thelight transmissive panel 101 is mounted in the carrier 110.

FIG. 16 shows a schematic exploded perspective view of the carrier 110and the sealing window 126. The arrangement as shown in FIG. 16 is thesame as shown in FIG. 13, except that the relative movement of thesealing window 126 with the respect to the carrier 110 during assemblyis perpendicular. That is, along direction B parallel with the normalaxis 107. Similar to the embodiment as shown in FIG. 13, the sealingwindow 126 comprises a plurality of reference surfaces which are notpart of the deformable seal 806. Each of pegs 1600, 1606 and snap-fitlatches 1602, 1604 comprises a reference surface for alignment. FIG. 16shows pegs 1600, 1606 for engagement with holes 1608, 1610. FIG. 16 alsoshows resiliently deformable latches 1604, 1602 for snap-fit engagementwith holes 1612 and 1614.

A further mounting unit 140 may be provided between the sealing window126 and the light transmissive panel 101, as schematically illustratedin FIG. 5a . The mounting unit 140 may comprise a resilient materialthat allows the sealing window 126 to assume a secure fixed positionrelative the light transmissive panel 101. The sealing window 126 mayhave a corresponding groove into which the mounting unit 140 may besecurely positioned.

A method 200 of assembling a touch sensing apparatus 100 is provided.FIG. 6 illustrates steps of the method 200. The order in which the stepsof the method 200 are described and illustrated should not be construedas limiting and it is conceivable that the steps can be performed invarying order. The method 200 comprises fixing 201 a substrate 106having a plurality of light emitters 103 and detectors 103′ to a carrier110, and attaching 202 the carrier 110 around a perimeter 104 of a lighttransmissive panel 101. The method further comprises arranging 203 thesubstrate to extend in a direction 107′ parallel with a normal axis 107of a plane 108 in which the light transmissive panel 101 extends,whereby the plurality of light emitters and detectors 103, 103′, arearranged above the touch surface 102. The method 200 thus provides for afacilitated assembly of the touch sensing apparatus 100 while achievingoptimal alignment, robustness, and accuracy as described above inrelation to FIGS. 2-3.

As mentioned, the carrier 110 may be formed from a single monolithicpiece of material, and the carrier may form a cavity 116 having walls117 at least partly enclosing the substrate 106. At least one of thewalls 117 may comprise openings 115, 115′, 115″. The method 200 maycomprise fixing 204 the carrier 106 to a display unit 121, 113, byfixing mounting elements 114 through the openings 115, 115′, 115″,thereby providing for the above mentioned advantages.

The method 200 may comprise adjusting 205 a distance 120 between thelight transmissive panel 101 and a display unit 113, 121, along thenormal axis 107 by attaching 207 the carrier 110 to the display unit113, 121, at least two different adjustable positions 119, 119′, along adirection 117″ parallel to the normal axis 107. Control of the distance120 is improved and facilitated, and may thereby be more easilyoptimized to various applications of the touch sensing apparatus 100.

The method 200 may comprise adjusting 208 a radius of curvature of thelight transmissive panel 101 in the direction of the normal axis 107 byattaching 209 the carrier 110 to a display unit 113, 121, at least twodifferent adjustable positions 119, 119′, along a direction 117″parallel to the normal axis 107. Control of the curvature of the lighttransmissive panel 101 is thus improved as described above.

The invention has mainly been described above with reference to a fewembodiments. However, as is readily appreciated by a person skilled inthe art, other embodiments than the ones disclosed above are equallypossible within the scope and spirit of the invention, which is definedand limited only by the appended patent claims.

For example, the specific arrangement of emitters and detectors asillustrated and discussed in the foregoing is merely given as anexample. The inventive coupling structure is useful in any touch-sensingsystem that operates by transmitting light, generated by a number ofemitters, inside a light transmissive panel and detecting, at a numberof detectors, a change in the received light caused by an interactionwith the transmitted light at the point of touch.

What is claimed is:
 1. A touch sensing apparatus, comprising: a panelcomprising a touch surface, a back surface, and an edge surface; asupport structure comprising a first portion and a second portion, saidfirst portion extending parallel to the edge surface of the panel, saidfirst portion extending above and below the touch surface, said secondportion extending parallel to the touch surface, and said first portioncomprising a first recess configured to secure a substrate to the firstportion, an emitter positioned on the substrate and above the touchsurface, said emitter configured to transmit light in a plane above thetouch surface and perpendicular to a normal of the touch surface; and anoptical element configured to be secured between the touch surface andthe second portion of the support structure, said optical elementcomprising a first surface configured to receive the transmitted lightfrom the emitter and a second surface configured to receive lightpropagating across a touch interacting portion of the touch surface,wherein the first surface is separated from the emitter by a spacing. 2.The touch sensing apparatus of claim 1, wherein the optical elementcomprises a light collimating surface.
 3. The touch sensing apparatus ofclaim 1, wherein the support structure further comprises a third portionextending parallel to said first portion, said first and third portionsforming a cavity configured to receive the substrate.
 4. The touchsensing apparatus of claim 3, wherein the third portion comprises asecond recess aligned with the first recess, wherein the second recessis further configured to secure the substrate.
 5. The touch sensingapparatus of claim 1, wherein the optical element is configured to slidebetween the touch surface and the second portion of the supportstructure.
 6. The touch sensing apparatus of claim 1, wherein theoptical element is configured to be secured to the second portion alonga third surface and wherein a fourth surface, opposite the thirdsurface, contacts the touch surface.
 7. The touch sensing apparatus ofclaim 6, wherein the fourth surface contacts only the touch surface. 8.The touch sensing apparatus of claim 6, wherein the optical element isconfigured to be secured against the touch surface by only the secondportion.
 9. The touch sensing apparatus of claim 1, wherein light fromthe emitter can directly reach an edge of the optical element where thesecond surface and touch surface meet.
 10. The touch sensing apparatusof claim 1, wherein the optical element contacts only the second portionand the touch surface.